The present invention relates to a sheet cutting and separating device using endless sheets with perforation along the edges for purposes of a sprocket type transport; furthermore the sheets are to have transverse tear perforations and are to be used in printers such as matrix printers, typewriters, word-processors etc. It is, moreover, assumed that the invention be practiced in an environment in which sprocket or traction devices are used for guiding the sheet and includes furthermore a sheet guide structure arranged above the casing of the machine.
Sheet separating structures usually serve to facilitate tear off of a completed form possibly with several copies. These structures permit tearing off by hand, possibly without tear edge. The known structures, however, render the overall construction of a printer or a typewriter rather cumbersome, and they become complex and are not very conveniently operable. The construction of such sheet separating device is moreover usually designed for processing the sheet stock in a stretched state. Obtaining the stretched state is an advantage for tearing because in the case of a bulky layer forms the cover as well as the lowest sheet wil not be shifted through unequally long paths.
Sheet-guiding structures with traction devices and traction flaps are known for example through the German printed patent application No. 3,036,642. The traction flaps can be pivoted away in order to thread the edge holes of the paper into the paper guide structure. After the sheets have been inserted, pins of the traction transport the paper and impart upon the paper the requisite advance and feed forces. This kind of paper guide structure requires a certain gap spacing between the traction flaps and the surface of the paper in order to make sure that the tractor flap will not impart a braking force through friction upon the paper merely by engagement. Moreover it must be made sure that only the pins entering the apertures along the edges provide the full advancing force upon the bundle of sheets in their entirety. Depending upon the number of copies overlaid this gap may be filled completely.